Three possibilities come to mind:
Is there an evolutionary purpose?
Does it arise as a consequence of our mental activities, a sort of side effect of our thinking?
Is it given a priori (something we have to think in order to think at all)?
EDIT: Thanks for all the responses! Just one thing I saw come up a few times I’d like to address: a lot of people are asking ‘Why assume this?’ The answer is: it’s purely rhetorical! That said, I’m happy with a well thought-out ‘I dispute the premiss’ answer.
If I found out that I don’t have free will, I would start trying to gain it back immediately.
What if you found out that free will is an inherently flawed concept and therefore impossible to conclusively obtain
if you found out that free will is an inherently flawed concept
I also cannot imagine finding out that the hole in my ass is bigger than I am.
What if you never had it and never can have it because its not a havable thing